Grinding and drying apparatus



5 Sheets-Sheet 1 J. E, BELL GRINDING AND DRYING APPARATUS Filed Jan. l2. 1922 sept. 6, 1927.

ATTORNEYS.

1,641,409 Sept. 6, l927 J, E. BELL GRINDING AND DRYING APPARATUS Filed Jan. l2, 19422 5 Sheets-Sheet 2 sept. 6, 1927. 1,641,409

- J. E. BELL GRINDING AND DRY'ING APPARATUS Filed Jan. l2, 1922 5 Sheets-Sheet 3 MJA/ g IN1/EN TOR. 4 BY A/ l E' i ATTORNEYS.

sept. 6, 1927; 1,641,409

J. E. BELL GRINDING AND DRYING APPARATUS Filed Jan. 12, 1922 i 5 sheets-sheet 4 naw/55s.A

BY M141/ :j ATTORNEYS.

Sept. 6, 1927.

J. E. BELL GRINDING AND DRYING APPARATUS Filed Jan. l2, 1922 5 Sheets-Sheet 5 \\\O o O0 INVENTO R.

Patented Sept. 6, 1927.

UNITED STATES PATENT ori-"ICE,

JOHN E. BELL, OF BROOKLYN, NEW YORK, ASSIGNOR TO COMBUSTION ENGINEERING CORPORATION, A CORPORATION OF NEW YORK.

GBINDING AND DRYING APPARATUS.

Application led January 12, 1922. Serial No. 528,668.

My invention relates to grinding and drying apparatus especially useful `for pulverizing and drying fuel such as coal that is to be burned in powdered form. I aim to make both the crushing or grinding andthe drying operations rapid, continuous eliicient, and economical, and to enable them to be carried on concurrently. I also aim to make the apparatus itself simple, durable, and relatively inexpensive. How these and other advantages can be realized through the invention will appear from my description hereinafter of the best forms of embodiment at present known to me.

In the drawings, Fig. 1 shows a vertical axial sect-ion through an apparatus conveniently embodying my invention and comprising a couple of similar grinding and drying mills or units arranged and connected to operate upon the same coal successively.

Fig. 2 is a. transverse view showing one of the grinding units opened up, with certain parts in section as indicated by the line 2-2 in Fig. 1,-a. fragment of the casing in front ot the plane of section appearing.

Fig. 3 is a transverse View of the interior of a unit opened up, taken as indicated by the line 3-3 inFig. l.

Fig. 4 shows a vertical axial section, on a larger .scale` through a single grinding and drying unit of somewhat different construction from those shown inl Figs. 1, 2 and 3.

Figs. 5 and 6 show transverse vertical sections through this grinding unit, taken as indicated by the lines 5-5 and 6 6 in Fig. 4.

Fig. 7 shows a vertical axial section through still another form of grinding and drying unit.

Fig. 8 is a fragmentary side view oi a partition shown in Fig. 7, taken as indicated by the line 8 8 in that figure.

The apparatus shown in Fig. 1 comprises a conduit, comprehensively indicated by the numeral 10` in which grinding mill units 11, 12 are serially arranged. The conduit 1() may be extended to include any desired number of grinding mills by simple cumulation of units, or a single grinding unit may be used by itself,since each one may be intrinsically complete. The units 411, 12

shown being almost exact counterparts of one another, it will suiice to describe in full detail only the unit 11.

The grinding mill 11 comprises a casing or shell 15 having at its opposite sides hollow journals 16, 17 by means of which it 1s supported for rota-tion in water-cooled bearings 18. Since the hollow journals 16, 17 form part of the conduit 10 and serve for entrance and discharge of material to and from the casing 15, I 'ordinarily prefer not to make them stationary axles, but rather to construct them as trunnions united and turning with the casing. The casing 15 may be driven (see also Fig. 2) from a countershaft 20 at the rearof the conduit 10, by lmeans of a sprocket chain connection 21 between a sprocket wheel 22 fast on the journal 16 and a sprocket wheel 23 on the shaft 20.

Coal is continuously fed into and through the casing 15 and the grinding devices therein by means of a rotary -screwconveyor 25 in the entrance journal 16,-which conveyor (especially since the grinder and drier 11 is shown as the first of the series inthe conduit 10) may be driven separately from the rotary lparts of the mill 11,-either by a special connection from the countersha'ft 20, or quite independently. -It is shown asof relatively coarse pitch, so as to `handle readily the coarsest material that it can hand e,-or that the mill 11 is intended to operate on. For reasons which will appear hereinafter, I generally prefer ynot to rely on the incoming coal to crowd the ground coal leavingthe mill 11 along through the discharge journal 17 and the rest of the conduit 10 leading to the unit 12, but (as here shown) to make special provision for feeding along and discharging the ground coal by means of a rotary screw conveyor 26 in said journal 17. For reasons which will presently appear, this screw conveyor 26 is not made with a solid central shaft like that of the conveyor 25, but consists simply ot a helically twisted strip of metal open through its center and secured at its outer edge to the interior of lthe journal 17.

vThe rotating discharge trunnion 17 of the mill 11 is connected with the rotating entrance trunnion 27 of the mill 11 by means of a short stationary section 28 of the conduit l0 which has a close fitting rabbeted joint with each of vsaid journals, but really belongs to the unit 11 rather than to the unit 12.4 The screw conveyor 26 of the journal 17 extends clear through the sta vtionary conduit section 28 just about iiush` with its further end, and so carries along and delivers the coal `to the journal 27, where it is, in turn,'taken and carried along by means or" a rotary screw conveyor 29 in said latter journal. Functionally, this conveyor 29 corresponds to the conveyor 25; but in form and construction it is like the conveyor 26., llt extends just about flush with the receiving end oit the journal 27. Aside yfrom the ditlerence between the rotary conveyors 25 and 29 just described, the mill unit 12 is shown as the exact counterpart of ythe unit 11, and may be individually driven from the countershaztt 2() in the very same manner.

Since the coal entering the conduit 1 0 is likely to contain more moisture than it is desirable to have present in the hnal powdered product, and since the grinding ot' the coal tends to facilitate disengagement ot moisture (and other gases orvapors), 1t is often advisable to heat the coal during` its passage through said conduit. rllhis l prefer to dowhile it is being ground in the mills 11 and 12., Accordingly, ll have shown a serpentine heater casing 30 surrounding and I enclosing the casing i5 of each cisaid mills l1 and l2, for the passage of heating medium over them. As shown, the journal beary ings 18 for the various journals are excluded rom the casing 30, and, also theirdriving means 2l, 22, etc., and the stationary c onduit sections 28 with their rabbeted joints above lnentioned,so as not to expose any of these parte to the heating medium., As

here indicated, the heating medium traverses the mills 11, 12 in series, iirst making an upward pass around the mill 11., then an idle longitudinal pass, then a downward pass around the mill 12, and then a longitudinal passv which may lead either to another mill unit or to a stack or other means of discharge. To in the transmission of heat from' the iiowing gaseous or vaporous heating medium to the coal in the casings v 15, the latter are'provided with external titi heat-transmitting projections in the form of a great many ifrustroconical protuberances on their opposite sides.

The ground coal being carried along in the lower portion of the journal 17 by the conveyor 26 instead oi being forcibly crowded through so as to hll the journal completely, .and the center of the conveyor being open, space is ailnorded tor passage and collection of vapor disengaging from the coal during and after the grinding operation, This mance therefore, is drawn through a mill toward` its fuel discharge end, and is drawn otf Jfrom the conduit 10 atin'tervals, from just beyond each grinding mill included in said conduit. y

At the periphery of thel two-part casing 15 is a circular liner band or track 40 on 'which a couple of tire-like annular members 41., l2 roll free and upright, one within another, under lateral guidance of members 43, il (see also lFigs. 2 and 3) on the sides of the casing. 'llhe track ll0 should pretn erably be of very hard steel (such as manganese steel) and the tires e1, 42 of ordinary tire steel such as used for the tires of wheels ior railway rolling stock. With track .and tiresll, l2 substantially cylindrical and relatively smooth, as shown-rather than conical or transversely toothed or serrated,- the particles of material being ground can move ireely across and along the track, so

as to be more readily and certainly acted on at each revolution of the track. .The interior oit the tire (and, in the present instance, the whole center of the casing 15) is occluded .by a transverse central partition or web l5 across the inside of the inner steel .tire 42. The four members 43 are in the term of frange webs or vanes extending more or less nearly radiallyv in the entrance side of the casing 15. The four members 44 are in the form of slightly curved flange webs or varies, extending morel or less nearly radially in the discharge side of the casing 15 and coming together at its discharge opening through the journal l?. The webs or vanes el have transverse iianges 46 which extend torwardl in the clockwise direction of rotation (speakingwith reference to llig. 2) of the casing 15, and increase in width toward the centen-where they curve toward the discharge opening at their merger Vwith. .the axially extending portions of the' webs, so as to assist in guiding and directing the ground coal to said opening.

As the casing 15 revolves, thetires d1, i2 roll on the internal track t0 and one on the other (the interior of one tire being a track to that inside it) under the influence of gravity, always remaining substauitially at the low point ot the track. The portion keeps the accumulation of coal falling into the entrance side or chamber ati-of the cas ing 15 from passing freely inside the tires Ill, a2 tothe discharge side or chamber 47, and thus coacts with the revolving vanes 4:3

llG

in causing the coal to be carried up and directed across the internal track 40 and the peripheries of the tires, through the gaps that exist between them everywhere above the low points. The coal progressively crushed under the weight of the tires is fed across the track 40 and the inner surface of the tire 41 by the pressure of fresh coal continually 'entering between the tires. The ground coal thus fed throu h the gravitational grinding means just described dro s in the discharge chamber 47, and is cau lit by the revolving discharge vanes 44,-eit er directly, or after some Aaccumulation has oc curred. By these vanes 44, the'ground coal is lifted until it slides down and out into the discharge journal 17.

The gravitational tire grinding mill shown in Figs. 4, 5 and 6 differs from that just described in having on its track three tires, 51, 52, 53, rolling upri ht one within another, instead of two. ts really important difference, however, is in the provision of .partition means, etc., for directing the coal to be ground back and forth across the peripheries of dierent tires in succession. Besides being occluded by the central partition 54 in the inner-most tire 53, the interiors of the tires and the center of the casing are also occluded by a transverse dished partition 55 in its entrance side which divides the latter into two chambers 56, 57. This partition 55 is attached to its side of the casing by circumferential s aced webs 58 at an intermediate point an by radial webs 59 at its periphery. The webs 58 assist in distributing the entering coal more Aor less uniformly, and the webs 59 in carrying it up as the casing orshell revolves and directing it across the track 50. The annullar opening aroundthe partition 55 is 'of such width relatively to the outer tire 51 that the partition itself directs the coal l mill described above the chambers at oppoacross the track 50 and the periphery of the tire 51. On the hollow side of the partition 55 are four radially extending vanes or webs 61 whose arrangementy and functions are similar to those of the varies 43 in Figs. 1 and 2,--as will presently appear.` In the discharge side or chamber 62 are four radially extending webs or vanes .63 which .differ fromfthe discharge vanes 44'in Figs. 1

and 3 principally in not being curved and in having transverse flanges 64 that do not extend far outward from their merger at their intersection. In the outer portion of the casing is a sloping partition 65 that extends circumferentially from one vane 63 to another, and serves as a reguide 'for directing bacirlacross the inner surface of the outer tire 51 (between it and the periphery of the ltire 52) ground coal that has crossed the tracl 50. The coal thus directed between the tires 51 and 52 against the hollow o lished partition 55 is by the latter redirected back again between thetires 52 and 53 to the discharge chamber 62. ,It is there caught by the'discharge vanes 63 and by them raised until it slides down and out into the discharge journal 17 In this mill, therefore, the coal is ground and reground lin a succession of distinct operations.

In the gravitational grinding mill shown in Figs. 7 and 8, a transverse central partition clamped between the halves. of the casing or shell-divides it into entrance and discharge chambers 71 and 72. The central portion of this partition 70 is solid and occ'ludes the center of the casing completely, so as to prevent the coal entering from passing directly through. In the outer zones of the partition 70, adjacent the peripheries of the chambers 71 and'72, are openings 73 (consisting of a great number of small holes) `for the passage of coal ground in the chamber 71 to the chamber ,72. The gravitational grinding means here employed comrises a quantity of balls in each chamer, of such sizes that they7 are incapable vof passing through the ho es 73 from one chamber to another. As the casing revolves, the balls 75 are continually tumbled about with the coal and effectively pulverize it. As the coal enters and is ground in the entrance chamber 71, it works its way radially outward therein and through the holes 73 into /the discharge chamber 72, where it is reground. It then works its way (or is displaced) into the discharge journal 17. In this mill also, therefore, the. coal is ground and reground in a succession of distinct operations.

The balls 75 may be of any suitably hard material, such as cast iron, The partition or diaphragm 70 may be of manganese steel, and the halves of the casing or shell may have dished linings 76 of the same material.

It will be noted that in all the forms of {site sides of the central partition are of relatir ly narrow width and convergent toward itheir peripheries, and that their slo ing outer sides tend to crown the materia toward the center and so help in feeding it along or in insuring its being picked up by the various revolving vanes. In addition, the convergence of the narrow chambers out- .ward in Fig. 7 crowds the falling balls together and so makes their action on the material more effective.

What I claim is:

1. A continuous rinding mill comprising a rotary casing wit means for entrance and dischar. e of material; gravitationally movable grinding means in said casing; means for heating the material while being ground; and means for drawing vapor disengaging from the material toward the fuel discharge end of the apparatus, and withdrawing and 2. A continuous grinding mill comprising a rotary casing with means for entrance and discharge of material; gravitationally movable grinding means in said casing; means `for continuously feeding material intovand out of said casing, and through said grinding means; means for heating the material while beingground; and means for withdrawing vapor from the material discharging means.

3. A continuous grinding mill comprising a rotary casing with hollow journals at opposite sides thereof for entrance and discharge of material, respectively; gravitationally movable grinding means 1n said casing; and means for drawmg od from the discharge journal vapor disengaging from the ground material.

4. A continuous grinding mill comprising al rotary casing with hollow journals at opposite sides thereof for entrance and discharge of material, respectively; gravitationally movable grinding means in said caslng; means for discharging the ground material through a portion of the discharge. journal, leaving space therein open for vapor disengaging from the ground material; and means for drawing od such vapor trom such open space separate from the ground material.

5. A continuous grinding mill comprising' a rotary casing with hollow journals at opposite sides thereof tor entrance and discharge of material, respectively; gravitationally movable grinding means 1n said casln'g; discharge means for the ground material including a rotary screw conveyor in the discharge journal; and means for drawing off from the upper side ot' said discharge means vapor disengaging from the ground material. Y

6. The combination of a continuous grinding mill comprising a rotary casing with hollow journals at opposite sides thereof tor entrance anddischarge of material, respectively, and gravitational grinding means in said casing; and a heater casing for passage of heating medium over said casing surrounding and enclosing the same to the exclusion of its journal bearings.

7. A continuous grinding apparatus com-` prising a conduit with rotary gravitational grinding mills therein, including hollow journals for said mills; and rotary means in 4said journals for continuously feeding material from mill to mill through said conduit.

8. A continuous grinding apparatus comprising a conduit with rotary gravitational grinding mills therein; means for heating the material ground during its passage throu h the conduit; and means for drawing o from said conduit, at intervals, vapor disengaging from the ground material.

9. A continuous grinding apparatus comprising a conduit with rotary gravitationaly grinding mills serially arranged therein; means for heating said mills; and means for drawing od from said conduit, beyond each mill, vapor disengaging from the ground material.

10. The combination of a continuous grinding apparatus comprisingl a conduit with rotary gravitational grinding mills serially arranged therein and journal bearings for supporting saidv mills; anda serpentine heater casing for passage of heating medium in series over said mills surrounding and enclosing them to the exclusion of their aforesaidjournal bearings.

l1. The combination of a continuous grinding apparatus comprising a conduit with rotary gravitational grinding mills serially arranged .therein andjournal bearings for supporting said mills; means for driving said mills individually; a serpentine heater casing. for passage of heating medium in series over said millssurrounding and enclosing them to the exclusion of their aforesaid journal bearings and. individual driving means; and means for drawing off from said conduit beyond each mill vapor disengaging from the ground material.

12. A grinding mill comprising a rotary casing with an internal track; a rotary tire adapted to roll on said track as said casing revolves; another rotary tire adapted to roll upright inside the one aforesaid; transverse partition means occluding the interior of said tire and serving to direct material entering the casing across said track; and reguide means at the far side of said track for directing material crossing the same back across the inner surface of the first-mentioned rotary tire.

13. A grinding mill comprising a rotary casing with means at opposite sides thereof for entrance and dischargev of material, respectively, and an internal track; a transverse dished partition in the entrance side of the casing occluding its center and serving to direct material entering it across said track, said partition having radially extending webs or flanges at its own hollow side away from the casing entrance; a plurality of radially extending Websor flanges in the discharge' side of said casing .coming together at its discharge opening; 'and rotary tire crushing and grinding means adapted to roll upright on said track under guidance of the aforesaid webs at opposite sides thereof.

14C. A grinding mill comprisin a rotary casing with means at opposite si es thereof yalor entrance and discharge of material, respectively, and an internal track; a transverse dished partition in the entrance side of the casing occluding its center and serving to direct material entering it across said track, said partition having radially extending webs or anges at its own hollow side away from the casing entrance; a plurality of radially extending webs or anges in the discharge side of said casing coming together at its discharge opening; rotary tires adapted to roll u right one within another on said track un er guidance of the aforesaid webs at opposite sides thereof; and circumferentially extending reguide means at the discharge side of said `tires for directing material back between them against said transverse partition means for vre-directionv back again vto the discharge.

15. A continuous grinding ball'mill comprising a rotary casing with means at opposite sides thereof for entrance and discharge of material, respectively; transverse partition means in said casing dividing the same of passing from one to the other through said openings.

16. A continuous grinding ball mill comprising a rotary casing with hollow journals at opposite sides thereof for entrance and discharge of material, respectiveldyl; transverse partition means in said casin viding the same into a plurality of chamgbers of narrow widthwith sides convergent toward their peripheries, and having openings therethrough adjacent the peripheries of the chambers for passage of ground material from chamber to chamber; grinding balls in said chambers 0I' such dimension as to be incapable of passin from one to the other through said openings; rotary means in said entrance journal for feeding the material through said chambers; and rotary means in said" discharge journal for withdrawing the material from said casing.

In testimony whereof, I have hereunto signed my name.

JOHN E. BELL. 

